Perforated indented screen



Nov. 17 1925- H. s. wooDwARD APER.FORA'IIEID INDENTED SCREEN Filed Feb. 27, 1924 2 Sheets-Sheet l INVENTO? Nov. 17,1925. 1,561,632

H. S. WOODWARD PERFOHATED INDENTED SCREEN /NVENTF 5 sition thereon of Patented Nov. 17, 1925.

HERBERT S. OQDWARD,

`or cAnBoNnnfLr., ennnsYLuaNrA.

rnnroaarnn `rnnramnn SCREEN.

,ApplicationeledFebrnar'y 27, 1924. Serial No. 695,391.

To all wlw/mit may concern:

Be it known that LQHERBERT S. Woon ivanma citizen Vof the United States, and a resident of the city of Carbondale, inthe county of Lackaw'anna and State ofjPenn- Sylvania, .have invented certain nevVand useful Improvements infPerforated Indented "Screenauof which the following isa specification.

4My `invention relates to perforated indented screens for the screening of coal, ore and similar materials, and more particularly to the constructionofthe sci "eenplates themselves, and the` arrangement `and dispoindented projections opi erative Tto impart strength Vand rigidity to the plate and to evenly distribute.. over the entire surface vthereof .the `material bein`g screened asit ``passes over ortraverse's the length of the screen.

lt will be understood* that theindented perforated screen plates aregadapted to be used `as the bottom of y'a Jlong `inclined troagh-like ystrnctureto Whiohis imparted a .or longitudinally reciprocating motion by -fany suitable kinechanism" (not show/vn). Goal, slate,.ore orsimilar matcrials delivered to the highlend ofthe screen is caused to p gravitationally` traverse the length-0f thescreenand suchet the material as may be of a size to 4-pass through `the perforations of the screen ywill be separated outso that pieces of material` delivered at thc lower end of the screenivillbe ,larger than the perforationsin the screen.

.es the mechanisms'for imparting Vmotion to shaking screens for asserting coal Yand similarmaterials tol size are Well known, vit is deemed unnecessary .to illustrate such mechanism in` order to vunderstandiny invention which, as above stated, relates to structure of the indented plates, a seresof which .forms the bottom `of the screen. rFliese perforated plates, ingenerahare rectangulaii' in `formgare of thefullwidth of the screen in which they are to` be used; and a number of these plates are `secured together substantially end to `end `to .make a shaking screen of anydesiredlength.

Uu each of the'sheets of theT drawings is illustrated one plate and a portionof the Vnext adjacent plate of a screen.

'The objects of my invention. are to.pro vide a perforated plate provided with indented projections thereon disposed preferably symmetrically with respect to thelongitudinal axis of the plate, although in some instances the indented projections may be arranged symmetrically with respect to both the longitudinal axis and the `transverse axis of the plate.

A further object `of my invention -is to provide such a shape and arrangement or disposition of the indented projections on a screen plate that they may be pressedinto the sheet with a single die not substantially larger than half the area of the plate.

A further object of my invention is to provide a perforated screen plate with in- `dentations which Will not unduly retard the passage of the material over the screen and at the same time to provide a` type or kind of indentation which will cause the loose material passing over the screen tolbe thor* oughly agitated `and travel a substantially zigzag path over a screen plate.

`It is to be understood that screen plates are made of comparatively thin s heet metal tofacilitate the punching therein of t-he perforations through which theinaterial 1is to be screened, `but in punching such plates with such perforations the sheet necessarily becomes more or less unevenly stretched and consequently warped so that the surface of a plate which is merely perforated is wavy or uneven, all of which undesirable in these screens.

lit is to be further understood that screen plates, made of thin `flat sheet material, necessarily bend orlex downwardly toward the middle or longitudinal axis of the screen when a load or charge of loose material is passing thereover and that this bending of the screen plates at their longitudinal axis or median line tends to concentrate at the middle of the screen the material traversing therethrough, thus preventing a` thorough and complete screening of the material or the asserting of the material to a predetermined size.

It is the object of my invention to provide .such a perforated plate with indentations or indented projections of such a nature and so disposed over the surface thereof such as will straighten the plate during the indenting process, take up the unevenly stretched materialformed during the perforating or punching process, and render the plates fiat,

.except for the projections indented therein,

and strong and sti llt) A further object of my invention is to provide projections which will tend to tilt and agitate the pieces of coal, slate, etc., passing thereover, so that smaller pieces will not ride on the larger pieces to be carried thereon and delivered together therewith out of the screen at the lower end thereof. The object of my invention is to provide the perforated plate with projections over which the material will rockand topple to thoroughly agitate the material passing thereover, thereby giving the smaller pieces ample opportunity to fall through the perforatlons.

A further object of my invention is to so arrange the indentations of one row as to overlap those of an adjacent row creating a ractically continuous indented surface which takes up the stretch produced in the sheet by the perforating process to which it has been previously subjected.

A further object of my invention is to provide a perforated screen plate with indented projections in the form of low triangular pyramids, one base-line of each of which is parallel to the longitudinal axis of the plate and screen and with the two baselines extending outwardly from the longitudinal axis of the plate, or inwardly toward the longitudinal axis of the plate, depending upon whether the indentation is to be used to spread the material outwardly toward the edges of the screen in the one case, or to concentrate it toward the middle of the screen in the other case.

A further object of m invention is to provide a screen plate of t e character above described, with indentations in the form of triangular pyramids directing the material outwardly toward the sides of the screen during its passage thereover and with the inclined riflles tending to concentrate or direct the material inwardly toward the middle of the plate, said ritlies or ridges being` successively of increasing height and preferahly increasing width outwardly from the longitudinal axis of the plate.

A further object of my invention is to provide a perforated screen plate with rows of triangular' projections operative to cause the material passing thereover to move outwardly toward the sides of the screen and to provide between said rows of projections ritlles of successively increasing height and width as the series of riffles approach the sides of the plate to offer increasing resistance or impedence to the lateral llow of material as it approaches the sides of the screen, and with series of parallel riftles between the side of the screen and the first row of projections to concentrate the material passing thereover and to direct it toward Vthe longitudinal axis of the screen.

Other objects of my invention will appear in the specification and claims below.

ln the drawings forming a part of this specification and in which the same reference characters are employed throughout the various views to designate the same parts,

Fig. l is a plan view of a portion of a shaking screen trough showing one complete indented screen plate and a portion of a second like plate secured thereto as they would be secured together to form the perforated bottom of a shaking screen;

Fig. 2 is a transverse vertical section on the line 2-2 of Fig. l;

Fig. 3 is an enlarged fragmentary plan view of the lower left hand corner of the plate shown in Fig. l,

Fig. 4i is a view similar to Fig. l showing a modified form of perforated indented screen plate wherein concentrating ribs or ritlies are dispensed with, and the material is given a zigzag motion over the surface of the plate by pyramidal indented projections only, said projections being disposed symmetrically on the plate with respect to both the longitudinal and transverse axes of the rectangular plate;

Fig. 5 is a vertical sectional view on the line 5-5 of Fig. A;

Fig. 6 is a fragmentary enlarged view of the upper left hand corner of the plate shown in Fig. 4L.

Referring to Figs. l, 2 and 3, the sides 1-1 of a shaking screen are provided with a series of bottom plates 2-2, each rectangular in shape and having its side edges 3 3 secured to the sides 'l-l of the screen by bolts 4,-4. rIhe bottom pla-tes 2 may be overlapped at their adjacent edges and secured together by rivets or bolts 5 or they may be arranged with abutting adjacent edges. The screen thus formed and comprising the sides l-l and a series of bottom plates 2, is mounted or positioned at a relatively slight incline, with the receiving end higher than the delivery end, and a back and forth reciprocatory movement is imparted thereto, as is indicated by the doubleheaded arrow 6.

Each plate 2 is symmetrical with respect to its longitudinal axis or the longitudinal median line 7-7 of the screen, as to the indentations or indented projections formed therein. lt is to be noted that in referring to the plates shown in the drawings, I have considered the longitudinal axis of the plate to be the line midway between and parallel to the shorter sides of the plate, because that line is coincident with the longitudinal axis of a completed screen having its bottoni composed of a plurality of plates 2. ln other words, l to be shorter than it is wide.

The projections indented vinto the perforated screen consist of a. plurality of inclined rows 88, .Q -9, lO-lO of triangular pyramids ll symmetrically disposed with rehave considered each plate 2.

(iti

albanese spect to -a central `row `or series 12 of prefn erably quadrangular `pyramidal projections 13h14 positioned with one diagonal ofthe base o'l each coincident with the Vlongitudinal `axis or" the plateQ.

Between each adjacent row or serieso'f pyramidal projections is provided one `of a `'series oit ritiles or ridges 15-l5, `16--16 and 17-17,one of each pair being on opposite sides ol' the `longitudinal axis ofthe plate.

lBetween the outer rows 10-10 of projections and the side edges 3-3 of leach plate are provided ritiies 18-18, 19--19 and 230-20- These riltles are all preferably parallel on each side of the median line ofthe plate and converge as they approach the rear edge 21 ot the platevso as to tend to concentrate or move `the material passing thereover toward the central or longitudinal anis of the plate. The `two innermost riilles 1x3-15 preferably meet adjacent the rear endor edge 21 of the plate, forming what may be termedL a V-shaped rilile `15--15 embracing the central series or row 12 of projections 13-14- The rililes 15, 16, 17, 18, 19 and 20 are, generally speaking7 made of progressively increasing width and height from the middle or .median line of the plate 2 outwardlyitoward the sides oftheplate. Thus,`the rifHes 15 in the embodiment of my invention shown in Fig. l are preferably about one and one-halt inches wide and one-quarter ot'an inch in height, and the riiles 20 are preferably two and one-halt inches wide an."l [ive eighths of an inch in height. Between these two `extremes the intermediate ritiles increase gradually trom the dimensions oi the ri'les 15 to the dimensions of the rililes 20.

The heights olf the pyramidal projections 11, 13 and 14 are preferably alike and of the height of the rililes 15. These dimensions are merely given so that a fair idea of the proportions and relations of the various indented projections with each other may be immediately understood. The exact dimensions, of course, form no part of my invention inasmuch as they will vary 4depenf'ling upon the kind of material to be treated or screened and the size to `which it is to be assorted or graded by the operation ot the screen.

Substantially the entire surface of each screen plate 2 is covered with punched pertoi-ations 29 all ot' the same size. It is to be understood that these perforations 22 are preferably made in the plate before the pyrdmidal projections and ritfles are impressed therein because,` as above stated, the

perforating or punching process tends to warp the plates by expanding or stretching the metal7 and the impressing of the projections and rlii'les therein yafter the been completed taking up the enpunching process has straightens the plates by panded metal.

The front edge 23 oit the plates 2 `is prcl erably parallel with the rear cdgell and both may be provided with a row ot per- 't'orations 24 for rivets 5.

(lne baseline o' each oi the pyralnidal projections 11 is preferably disposed substantially parallel to the longitudinal median line '7--7 of the plate i2 and the other two base lines converge in a direction away from said line 7--7. One diagonal et' the bases of the quadrangular pyramids 13 and 1li is preferably arranged coincident with the median line `--7 of the plate 2.

l have :shown by arrows 25.011 the right hand half ot' the plate 2 the general direction of the pieces of coal forming the bottom oit a layer oi coal as it traverses that portion of the screen. The pieces near the center ot theiscreen will tend` to `be crowded laterally by the inclined tace o1 thepyramid 13 and toward the riliie `15. As the jogging of `.the screen continues and. the material moves on, some oit' it will pass over the side walls of thepyramid 13iand pass down toward the pyramid 1a. and `will there be de- `tlected toward the rilile 15. Part of the material will pass down the` screen between the pyramid 14 and the ritiie 9 and will be concentrated toward the middle ot the screen at the rear edge thereotI by the ril fles 15.

The piling up of the material between the pyramid 13 and the 'rilile 15 will torce some of the material over the riiile 15 and between the lirst two pyramids 1.1 of row 8 of projections 11,. Other ot themate rial will pass between the pyramid 13 and the riiie I15 and will accumulate. in the space between the pyramid and the ril-ile 15 1there the abovewdescribedoperation will be repeated.

`Material starting over the plate or screen from a position betweenriiiles `15 and 1G will be divided by the pyramid 11 of row 8, part of it tending to `move to the right toward the ritile 16 and a part of it passing between the pyramid 11 and the riiiie 16. Part ot that which accumnlatesup between the said pyramid 1.1 and the riitle 1 6 will pass down the screen between the pyramid 1 1 and the riiie 16, but some oi this material will be crowded over the riiiie ltinto the `space between the lirst two of the pyran'lids 11 ot the second series or row `9 ot pyramids S.

In this way the material is given a more or less zigzag motionu being spread laterally or outwardly toward the side ot the screen by the outwardly pointed inclined faces oi the pyramids 11, `153, 14 and being coneen* trated toward themiddle olfthescreen by the riflies 15 to 20 inclusive. `As the ri'liles increase in height in a direction away from the longitudinal axis T-T ot the screen, the movement ot the material toward the side of the screen is more and more impeded and the influence ot the inclined rillles increasingly predominates so that7 as a result olf this the material is prevented trom unduly piling up along the sides ot' the screen auf is liept in a comparatively even layer all over the screen.

is the large pieces or coal move over the apices ot the pyramids they topple oz' turn over causing any small pieces ot coal which are carried thereby to tall oli. ln this way during the traverse olf' the screen the small pieces or' a size to pass through the openings or pertorations in the screen have an op- All) portunity so to doj on accountot the jogging action or' the screen and the top ing the large pieces over the apices or L pyrain ilsj thus effecting a thorough screening or the coal to size. f

'ln ythe modilication shown in TFigs. l to 6, the riliies 15 to 20 inclusive heretofore described, are dispensed with and the periorated plates 2 are provided with a series ot rows of indented pyramids all ot substantially the same height. rlhe row l2 ot pyramids 13, 14 arranged alo-ng the longitudinal axis ot the screen comprises tour-sided or quadrangular pyramids having the diagonal ot their bases coincident with the longitudinal axis T-T ot the plate. The other pyramids 1l and ll are triangular. @ne hase line ot each ot the triangular' 'pyramids ll and 1l is arranged parallel to the median line 7-7 ot the plate. When a triangulaipyramid is to impart to the coal passing thereover a movement toward the side ot the screen, the other two sides ot the hase are directed outwardly toward the side oit the plate or screen as instanced in the pyramids 1l. 1When a triangular pyramid is to be used to concentrate the material passing over it toward the middle ot the screen the two converging sides or' the base point inwardly toward the median line 'i' ot the screen as instanced in the pyramids l1. The straight side ot the hase of each triangular pyramid is preferably approximately in line with the middle ot the adjacent hase line ot the next pyramid to the rear thereof.

ln the torm ot my invention shown in Fig. 4e, l. have shown three staggered rows El', 97 l0', respectively and one straight row 26 oit indented triangular pyramids extending longitudinally of each halt ot the screen and symmetrically arranged on opposite sides ot the row l2 ot pyramids.A 'lhose pyramids 1l wherein the apices ot' the 1cases extend outwardly or away trom the longitudinal axis 7-7 of the plate l term tor convenience spreading 'pyramids7 and those pyramids ll the apices ot the cases of which are directed inwardly toward the said axis l term concentrating pyramids. Thus, in stag- Leonesa gered row S l provide live spreading pyramids ll. ln the second row 9 are three spreading pyramids ll and trio concentrating pyran'iids ll, one at each end or the said row. rEhe third staggered row lili duplicates the second stages-red row in every particular'. The tourth straight row comprises three pyramids ll all ot' which are concentrating. rlhe course ot the material over the screen indicated by the arrows 'is the mainclinet ce or a is terial encounters the spreading pyramid 1l it is crowding outwardly away 'troni the median line ot the screen and as the material encounters the concentrating pyramid ll it will he moved inwardly toward the longitudinal axial line ci? the plate or screen.

ln this way the material in traversing' the screen will he kept evenly distributed over the screen and thoroughly agitated so that all the pieces or' coal or similar material or ay size to pass through the perforations in the screen will haveV an opportunity so to do during their travel oli he length ol the screen.

lt will he noted that the pyramid projection imprinted into the screen shown in Fig. d are disposed over the screen symmetrically with respect to both longitudinal and transverse axes ot the plate or screen and that the die for pressing these projections or indentations need oe only substantially onehalt the sise ot the plate7 thus a die as wide as the plate and long as three rows ol' indentations may he used to imprint the plate at two operations or a die as long as the plate and wide enough to imprint the central longitudinal row ot pyramids and those between them and the sides ot the plate may he employed.

Similarly, the plate shown in Fig. l may he imprinted into the perforated sheet in two operations with a die substantially as large as one-halt' ot' the sheet to he imprinted.

By so arranging the extensions symmetrically to one casting oit the plate, the cost of making dies tor pressing these screens is comparatively low and comparatively light, and light and inexpensive machinery may he employed for pressing the screens.

Having thus described my invention, what l claim and desire to protect hy Letters Patent of the United States is:

l. fr shaker screen comprising a perfon ated metal sheet or plate having rows of indented triangular `pyramidal projections disposed over the upper surface thereof a hase line ot each pyramid being parallel to thc axis ot the screen.

2. A shaker' screen comprising a perforated nietal sheet or plate having a plurality ot indented triangular pyramidal projections disposed over the upper surface thereol and arranged symmetrically with respect to an axis of said sheet or plate a hase line of each pyramid being substantially iii parallel to the longitudinal axis of the plate.

3. A shaker screen comprising a perforated metal sheet or plate having rows of indented triangular pyramidal projections disposed over the upper surface thereof and arranged symmetrically with respect to an axis of said sheet or plate, a base line of each pyramid being substantially parallel to the longitudinal axis'of the plate.

4. A shaker screen comprising a perforated metal sheet or plate having parallel rows of indented triangular pyramidal projections disposed over the surface thereof and rising therefrom, said rows being arranged symn'ietrically with respect to the longitudinal axis of said plate, a base line of each pyramid being substantially parallel to the longitudinal axis of the plate.

5. A shaker screen comprising a perforated metal sheet or plate having a plurality of indented triangular pyramidal projections disposed over and rising from the surface thereof.

6. A shaker screen comprising a perforated metal sheet or plate having a plurality of triangular pyramidal projections arranged over the surface thereof, one base line of each of said projections being substantially parallel to the longitudinal axis of said plate.

7. A shaker screen comprising a perforated metal sheet or plate having a series of quadrangular pyramidal projections disposed along the longitudinal axis of said plate and acting to direct the material passing thereover outwardly toward the longitudinal sides of said plate, and rows of triangular' pyramidal projections symmetrically disposed on opposite sides of the longitudinal axis of said plate and acting in the same manner.

8. A shaker screen comprising a perforated sheet or plate provided with rows of indented pyramidal projections acting to direct the material passing thereover outwardly toward the sides of said plate, with upwardly indented rilles between said rows of pyramidal projections acting to direct the material toward the longitudinal axis of said plate.

9. A shaker screen comprising a perforated plate, the surface thereof being provided with alternating parallel rows of spreading pyramidal projections and concentrating rilles.

10. A shaker screen comprising a perforated sheet or plate, having a series of quadrangular spreading pyramidal projections disposed with a diagonal of the bases thereof coincident with the longitudinal axis of said plate, and rows, symmetrically arranged on opposite sides of said axis, of triangular pyramidal spreader projections separated by concentrating rifiles, said rifiles being of in creasing height as the series of riflles progresses toward the sides of the plate.

ll. A shaker screen comprising a perforated sheet or plate and having its surface provided with inclined rows of pyramidal projections with a riftle between adjacent rows of projections, said ritles being of increasing height as the series of ritiles approaches the sides of said plate and disposed parallel to the adjacent rows of rilfles.

12. A shaker screen comprising a perforated metal sheet or plate having rows of indented triangular pyramidal projections disposed over the upper surface thereof and arranged symmetrically on opposite sides of the axis of said sheet or plate, the projections in one row being staggered with respect to the projections of the adjacent row, a base line of each pyramid being substantially parallel to the axis of said plate.

13. A shaker screen comprising a perforated inetal sheet or plate having a series of pyramidal projections disposed along the longitudinal axis of said plate, and rows of pyramidal projections symmetrically disposed on opposite sides of said plate, said projections acting to direct the material passing thereover outwardly toward the sides of said plate, and means adjacent the sides of said plate to direct the material from the sides of said plate inwardly toward said projections.

14. A shaker screen comprising a perforated metal sheet or plate having a series of quadrangular pyramidal projections disposed along the longitudinal axis of said plate and acting to direct the material passing thereover outwardly toward the longitudinal sides of the plate and rows of triangular pyramidal projections symmetrically disposed on opposite sides of the longitudinal axis of the plate, a base line of said triangular pyramids being parallel to the axis of said plate.

In witness whereof, I have hereunto set my hand this 25th day of February, 1924.

HERBERT S. WOODWARD. 

